The western U.S. oil refinery with the expensive galling problem
	Ready for inspection: an A-193-B7 3 ½ - 8 x 28” long stud and A-194-2H nut assembly

December 2006

Solved: costly galling problem for oil refinery

When a western oil refinery shut down two reactor towers recently for maintenance, mechanics couldn’t disassemble critical nuts and studs due to galling. Instead, they ended up cutting and scrapping the $453 assemblies – 36 in all, worth $16,300! Desperate for new parts that would arrive on time for start up, they scoured the internet and found Atlantic Fasteners.

Our Technical Service Director, Dan McKeeman, with 30 years of experience, was soon on the phone asking dozens of questions over several days. Next, he sourced 3 ½” diameter x 28” long studs, 2H nuts, and hardened flat washers to his custom specifications. Luckily, he was able to find a manufacturer which could deliver within the necessary four week window.

His four-pronged approach to eliminate galling was:

1. Using Aerospace standards to specify thread fit
2. Controlling the hardness ratio between the studs and nuts
3. Specifying thread quality and thread axis relationships
4. Calling out the proper anti seize interface for the application

So now, instead of the refinery throwing out the $453 nut and stud assemblies after one use, they can reuse them, saving $8,150 per tower, plus untold hours of costly labor!

And that doesn’t even include other downtime savings. One major expense is the outside contractor who spends four days scrubbing and recharging the towers at a cost of $375,000. To delay the crew, while mechanics wrestle with frozen nuts and studs, can quickly add tens of thousands of dollars to the final shut down bill.

Since solving the galling problem, Dan McKeeman has visited the refinery to discuss other fastener issues.